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Terminal Hydride Species in [FeFe]-Hydrogenases Are Vibrationally Coupled to the Active Site Environment.

ABSTRACT: A combination of nuclear resonance vibrational spectroscopy (NRVS), FTIR spectroscopy, and DFT calculations was used to observe and characterize Fe-H/D bending modes in CrHydA1 [FeFe]-hydrogenase Cys-to-Ser variant C169S. Mutagenesis of cysteine to serine at position?169 changes the functional group adjacent to the H-cluster from a -SH to -OH, thus altering the proton transfer pathway. The catalytic activity of C169S is significantly reduced compared to that of native CrHydA1, presumably owing to less efficient proton transfer to the H-cluster. This mutation enabled effective capture of a hydride/deuteride intermediate and facilitated direct detection of the Fe-H/D normal modes. We observed a significant shift to higher frequency in an Fe-H bending mode of the C169S variant, as compared to previous findings with reconstituted native and oxadithiolate (ODT)-substituted CrHydA1. On the basis of DFT calculations, we propose that this shift is caused by the stronger interaction of the -OH group of C169S with the bridgehead -NH- moiety of the active site, as compared to that of the -SH group of C169 in the native enzyme.

SUBMITTER: Pham CC

PROVIDER: S-EPMC6812543 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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Terminal Hydride Species in [FeFe]-Hydrogenases Are Vibrationally Coupled to the Active Site Environment.

Pham Cindy C CC Mulder David W DW Pelmenschikov Vladimir V King Paul W PW Ratzloff Michael W MW Wang Hongxin H Mishra Nakul N Alp Esen E EE Zhao Jiyong J Hu Michael Y MY Tamasaku Kenji K Yoda Yoshitaka Y Cramer Stephen P SP

Angewandte Chemie (International ed. in English) 20180723 33

A combination of nuclear resonance vibrational spectroscopy (NRVS), FTIR spectroscopy, and DFT calculations was used to observe and characterize Fe-H/D bending modes in CrHydA1 [FeFe]-hydrogenase Cys-to-Ser variant C169S. Mutagenesis of cysteine to serine at position 169 changes the functional group adjacent to the H-cluster from a -SH to -OH, thus altering the proton transfer pathway. The catalytic activity of C169S is significantly reduced compared to that of native CrHydA1, presumably owing t ...[more]

PMID: 29923293

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Terminal Hydride Species in [FeFe]-Hydrogenases Are Vibrationally Coupled to the Active Site Environment.

Publications

Terminal Hydride Species in [FeFe]-Hydrogenases Are Vibrationally Coupled to the Active Site Environment.

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